Numerical Research On Dynamic Response Of Reinforced Concrete Slab Strengthened With CFRP Subjected To Blast Load

Frequent terrorist bombings and accidental explosion accident not only brought huge economic losses and heavy casualties,but also caused great psychological pressure to the public,seriously threaten the social harmony and stability in recent years.lt has become an important research topic to take effective measures to improve the antiknock performance of buildings.Carbon Fiber Reinforced Polymer(CFRP)is very suitable for civil engineering due to the unique mechanical properties,good adhesion,heat resistance and corrosion resistance,,and has been widely applied in structural reinforcement of civil engineering.In order to study the mechanical behavior of reinforced concrete slabs strengthened with CFRP under blast loading,the dynamic response characteristics of reinforced concrete slabs strengthened with CFRP under blast loading were studied by means of theoretical analysis and numerical simulation.Main research contents and conclusions can be obtained as follows:(1)The elastic and plastic ultimate resistance of the reinforced concrete slab reinforced by CFRP is derived according to the equilibrium condition of stress and internal force by means of Navier solution.The Equivalent Single Degree of Freedom method is applied to the equivalent system of CFRP reinforced RC slab under explosive loading,in which the equivalent method from descending triangle pulse to explosive load.According to the calculation method of the dynamic response of the equivalent system proposed by TM5-1300,the maximum dynamic displacement value of the middle cross section area of the reinforced concrete two-way slab reinforced by CFRP is obtained by the equivalent single degree of freedom method.The correctness of the theoretical formula analysis is verified by the corresponding numerical simulation results.(2)A fully coupled model including CFRP cementation layer,concrete slab,reinforced skeleton,air field and TNT explosive is established based on the modeling method of separated model with common node by means of ANSYS/LS-DYNA.The nonlinear coupling effect between shock wave and CFRP reinforced concrete component is achieved based on stiffness penalty algorithm.The dynamic response characteristics of reinforced concrete slab reinforced by CFRP under explosive load are compared and analyzed by use of the ALE multi material fluid-solid coupling algorithm.The influence of the CFRP external paste.The thickness of CFRP and the boundary conditions of the reinforced concrete slab on the antiknock performance of the slab were analysed.The research results show that CFRP can significantly improve the anti explosion performance of the reinforced concrete slab,and the increase of the anti explosion performance of the plate is mainly due to the limitation of the expansion speed of the concrete crack in the tensile zone by CFRP,and thus greatly improving the flexural rigidity and the integrity of the reinforced concrete slab.The form of the CFRP and the reinforcement of the reinforced concrete.The boundary conditions of the CFRP external paste and the reinforced concrete slab are interrelated.Under different boundary conditions,the external form of CFRP is different for the increase of the anti explosion performance of the reinforced concrete slabs.The reason for this difference is the nature of the limitation of the CFRP for the crack expansion of the concrete material in the tensile zone.In addition,the maximum dynamic displacement of the reinforced concrete slab shows a nonlinear decreasing trend with the increase of the same gradient of the thickness of CFRP.It shows that the thickness of the CFRP is not the thicker the better,but exist the best value that both satisfy the need of economy and the force at the same time.The research results can provide theoretical suggestions and references for blast resistant design of reinforced concrete slabs strengthened with CFRP.(3)The smooth particle hydrodynamics(SPH)and the finite element method(FEM)are used to establish the full coupling model of the smooth particle-finite element(SPH-FEM).The numerical simulation of the typical reinforced concrete slab reinforced by CFRP are analyzed combined with ALE multi material fluid-solid coupling method.The results of contrast analysis show that SPH-FEM has a significant advantage in dealing with large deformation.The reasonable use of SPH-FEM coupling model can greatly improve the computational efficiency.However,due to the limit of the number of SPH smooth particles.the components will generate a serious stress concentration if the explosive model of SPH particles is used,but with the increase of the number of particles,the stress concentration will gradually weaken.The results of the dynamic response tend to be more realistic.